As many countries and regions have started large-scale deployment of smart meters, there is a growing amount of data on electricity use available for energy efficiency services. We have developed a novel tool that, based on smart meter data, automatically generates customised energy-saving advice to commercial and industrial customers. This type of audit tool could enormously expand the target of energy audits to almost all small- and medium-sized enterprises (SMEs) with smart metering at a low cost per customer. In this paper, we explain the structure of and approaches that we used in our prototype tool, such as fault detection, energy disaggregation, social comparison and benchmarking and selective visualisation. We also show test case results for the tool by using smart meter data from 34 public buildings in Japan. While the prototype tool presented in this paper has some limitations, the approach and the basic structure of the tool are valuable and provide the basis for more sophisticated tools.